The study examined the Influence of Secondary School Head Teachers' General and Instructional Supervisory Practices on Teachers' Work Performance. Qualitative and qualitative methods with a descriptive-correlational research approach were used in the study. Purposive sampling technique alongside random sampling technique was used to select the research participants from secondary schools. Self-constructed questionnaire and structured interviews were used as relevant tools to gather data from respondents. Descriptive statistics, frequency, percentage, and mean were used in analyzing data and reporting the study findings. And Pearson Correlation Coefficient was used to establish the extent of relationship between head teachers' supervisory practices and teachers' work performance. The study findings indicate that head teachers, to a great extent in private secondary schools; do not carry out instructional supervision albeit they do some informal classroom visits. They slightly do general and informal supervision at the expense of instructional or formal supervision. To this end, findings indicate that 64.3% of head teachers routinely check their teachers' pedagogic documents and as a practice of teacher supervision, while 57.1% of head teachers informally visit their teachers during classroom instruction. The findings of this study indicate that limited general and instructional supervision is commonplace in secondary schools. It is likewise revealed through the study findings that head teachers are unaware of their job description, are not given support to practice instructional supervision, and experience both role conflict and ambiguity in the course of completing the work of headship and teaching simultaneously. Also the study findings revealed that to some teacher participants, supervision is "nonexistent" in secondary schools due the fact that some of them have been teaching for more than a decade, but they have never been supervised by the head teacher in the classroom. The research findings likewise indicate a moderate correlation between secondary school head teachers' supervisory practices and teachers' work performance. The relationship existed at the 0.001 level (2-tailed) with Pearson Correlation Coefficient of 0.636. And the coefficient of determination was 0.4044 or 40% indicating a moderate relationship between supervision and teacher performance. Challenges related to teacher supervision were reported by study participants, mainly, head teachers. Private secondary school head teachers reported more challenges than their counterparts in government schools. Appended are: (1) Supervision Interview Question Guide for Research Participants; and (2) Supervision Questionnaire for Research Participants. (Contains 11 tables and 2 figures.)